<?php
session_start();
$a = array_merge(range(0,9), range('a', 'z'));
shuffle($a);
$text = $a[0] . $a[1] . $a[2] . $a[3] . $a[4] . $a[5];
$_SESSION['captcha'] = $text;

// Set the content-type
header("Content-type: image/png");

// Create the image
$im = imagecreatetruecolor(400, 30);

// Create some colors
$white = imagecolorallocate($im, 255, 255, 255);
$grey = imagecolorallocate($im, 128, 128, 128);
$black = imagecolorallocate($im, 0, 0, 0);
imagefilledrectangle($im, 0, 0, 399, 29, $white);

// Replace path by your own font path
putenv('GDFONTPATH=' . realpath('.'));
$font = 'images/tahoma.ttf';

// Add some shadow to the text
imagettftext($im, 20, 0, 11, 21, $grey, $font, $text);

// Add the text
imagettftext($im, 20, 0, 10, 20, $black, $font, $text);

// Using imagepng() results in clearer text compared with imagejpeg()
imagepng($im);
imagedestroy($im);
